The present invention relates to a new and distinct hybrid cultivar of Phlox plant, known as Phlox ‘Opening Act Ultrapink’ and will be referred to hereafter by its cultivar name or the “new plant”. The new plant was the result of a cross pollination of ‘Amethyst Pearl’ U.S. Plant Pat. No. 28,487 as the female or seed parent and Phlox carolina ‘Lil' Cahaba’ (not patented) as the male or pollen parent. The cross was performed by the inventor on Nov. 17, 2013 in the greenhouses at a wholesale perennial nursery in Zeeland, Mich., and seed was collected in the early winter of 2014. During the trial process the new plant was identified by the breeder code 14-24-2. ‘Opening Act Ultrapink’ has been asexually propagated by tip and basal stem cuttings in the greenhouses at the same nursery in Zeeland, Mich. since 2016, as well as by shoot tip tissue culture. The unique characteristics of the new plant have been found to be reproducible and stable in successive generations of asexually propagated plants and the resultant plants have been found to be identical to the original selection.